Several patents teach coiled composite springs and include the following:
Fiber material forms are proposed and include unidirectional or twisted fibers/tows (U.S. Pat. Nos. 4,473,217, 4,765,602 and 5,558,393), wound fibers (U.S. Pat. Nos. 5,549,370, 5,603,490, and 5,988,612), braided fibers (U.S. Pat. Nos. 4,260,143, 4,380,483, 4,434,121 and 4,976,812), and bi-directional fabrics (U.S. Pat. Nos. 4,489,922 and 4,773,633);
One series of patents (U.S. Pat. Nos. 5,549,370 and 5,603,490) suggest a core surrounded by an external xe2x80x9ccladdingxe2x80x9d of wound fibers at a specific orientation for optimum strength;
Selected composite (fiber-resin) material forms include resin bath impregnation/wet lay-up of dry fibers/fabric (stated or implied in almost all patents), and pre-impregnated tape and fabric;
Tooling materials include a cylindrical mandrel with grooves for location of the composite material (U.S. Pat. Nos. 4,260,143, 4,380,483, 4,473,217 and 5,558,393);
Some tooling concepts propose xe2x80x9ccontinuousxe2x80x9d molding processes where the mandrel rotates as new material is feed at one end and cured material is removed from the opposite end (U.S. Pat. Nos. 4,434,121 and 5,988,612);
One patent (U.S. Pat. No. 4,773,633) suggests drawing tubing over xe2x80x9cspring wirexe2x80x9d composed of resin saturated fabric strips wound in a helical manner at xc2x145xc2x0 over a rod shaped retainer to fix the shape of the spring wire; The patent states that it is beneficial if the tubing is heat shrinkable to xe2x80x9cpress excess resin out of the spring wire and prevent crack formation during curingxe2x80x9d. This can be done xe2x80x9cprogressivelyxe2x80x9d along the wire to drive out air inclusions. The patent also suggests that the same tubing can be eliminated by thermal or chemical decomposition.
The above enumerated patents are incorporated herein by reference.
The present invention provides a composite cord assembly ideal for shaping and molding into high performance structure such as coil springs, fencing, fishing rods, and golf club shafts. In fact, anything composed of a rod or tube-like cross-section can be fabricated with said composite assembly. In the coil spring area, for example, the cord assembly coils may be advantageously used in high performance racing cars where weight is of prime concern as well as for mountain bikes where weight and strength have driven the use of composite materials in frame design and other components. The invention also has application in the field of design of ultra modern lighting fixtures, for example, where cantilevered structures require strong light weight supports and where power or optical fibers may be advantageously passed through the cord assembly structure. In accordance with an embodiment of the invention, such power and/or optical fibers may be carried within a core region of the cord assembly. The invention also has use as a support structure for tables, in chair designs and the like where custom shaping may be combined with high strength and light weight.
The invention has the advantage of being flexible (or formable) for manipulation into desired shapes, and requires minimal (or no) tooling for fabrication into rigid structure. In one example, the composite assembly consists of a package of fibers enclosed by an external cladding.